The present invention relates to polyether ester elastomers, and manufacture and use thereof.
Thermoplastic elastomers (TPES) are a class of polymers which combine the properties of two other classes of polymers, namely thermoplastics, which may be reformed upon heating, and elastomers which are rubber-like polymers. One form of TPE is a block copolymer, usually containing some blocks whose polymer properties usually resemble those of thermoplastics, and some blocks whose properties usually resemble those of elastomers. Those blocks whose properties resemble thermoplastics are often referred to as xe2x80x9chardxe2x80x9d segments, while those blocks whose properties resemble elastomers are often referred to as xe2x80x9csoftxe2x80x9d segments. It is believed that the hard segments provide similar properties as chemical crosslinks in traditional thermosetting elastomers, while the soft segments provide rubber-like properties.
The weight and mole ratios of hard to soft segments, as well as the type of the segments determines to a great extent the properties of the resulting TPE. For example, longer soft segments usually lead to TPEs having lower initial tensile modulus, while a high percent of hard segments leads to polymers with higher initial tensile modulus. Other properties may be affected as well. Thus, manipulation on the molecular level affects changes in the properties of TPEs, and improved TPEs are constantly being sought.
Frequently the soft segments of TPEs are formed from poly(alkylene oxide) segments. Heretofore the principle polyether polyols have been based on polymers derived from cyclic ethers such as ethylene oxide, 1,2-propylene oxide and tetrahydrofuran. These cyclic ethers are readily available from commercial sources, and when subjected to ring opening polymerization, provide the polyether glycol, e. g., polyethylene ether glycol (PEG), poly(1,2-propylene) glycol (PPG), and polytetramethylene ether glycol (PO4G, also referred to as PTMEG), respectively.
U.S. Pat. No. 3,023,192 Shivers discloses segmented copolyetheresters and elastic polymer yarns made from them. The segmented copolyetheresters are prepared from (a) dicarboxylic acids or ester-forming derivatives, (b) polyethers of the formula HO(RO)nH, and (c) dihydroxy compounds selected from bis-phenols and lower aliphatic glycols. R is a divalent radical, and representative polyethers include polyethylene ether glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, and so on, and n is an integer of a value to provide a polyether with a molecular weight of about 350-6,000.
U.S. Pat. No. 3,651,014 Witsiepe discloses copolyetheresters consisting of recurring long chain and short chain ester units. The long chain ester units are represented by the formula: 
The short chain ester units are represented by the formula: 
R and Rxe2x80x2 are divalent radicals remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight of less than 300. G is a divalent radical remaining after removal of terminal hydroxyl groups from a long chain polymeric ether glycol, having a molecular weight greater than 600 and a melting point below 55xc2x0 C. D is a divalent radical remaining after removal of terminal hydroxyl groups from a low molecular weight diol. The copolyesters of this patent are prepared from dicarboxylic acids (or their equivalents), (b) linear long chain glycols and (c) low molecular weight diols; provided however, that there must be used either at least two dicarboxylic acids (or their equivalents) or at least two low molecular weight diols. A list of long chain glycols including xe2x80x9cpoly(1,2 and 1,3-propylene oxide) glycolxe2x80x9d is present at column 4; however, the examples are directed to the use of PO4G as the long chain polymeric ether glycol.
U.S. Pat. No. 4,906,729 Greene et al. discloses segmented thermoplastic copolyetheresters having soft segments formed from a long chain polyalkyleneether glycol containing 80 to 97 mole percent of copolymerized tetrahydrofuran and 3 to 20 mole percent of a copolymerized cyclic alkylene oxide, preferably copolymerized 3-methyltetrahydrofuran, and fibers and films with an improved combination of tenacity, unload power, melting temperatures and set.
U.S. Pat. No. 4,937,314 Greene discloses thermoplastic copolyetherester elastomers comprising at least 70 weight % soft segments derived from poly(alkylene oxide) glycols and terephthalic acid. The hard segments constitute 10-30 weight % of the elastomer and are 95-100% poly(1,3-propylene terephthalate). The specification discloses that the poly(alkylene oxide) glycols have a molecular weight of about 1,500-about 5,000 and a carbon-to-oxygen ratio of 2-4.3. Representative poly(alkylene oxide) glycols include poly(ethylene oxide) glycol, poly(1,2-propylene oxide) glycol, poly(1,3-propylene oxide) glycol, poly(tetramethylene oxide) glycol (PO4G), etc. In the examples, the soft segments are based on PO4G and tetrahydrofuran/ethylene oxide copolyethers.
U.S. Pat. No. 5,128,185 Greene describes thermoplastic copolyetherester elastomers comprising at least 83 weight % soft segments derived from poly(alkylene oxide) glycols and terephthalic acid. The hard segments constitute 10-17 weight % of the elastomer and comprises poly(1,3-propylenebibenzoate). The specification discloses that the poly(alkylene oxide) glycols having a molecular weight of about 1,500-about 5,000 and a carbon-to-oxygen ratio of 2.5-4.3. Representative examples include poly(ethylene oxide) glycol, poly(1,2-propylene oxide) glycol, poly(1,3-propylene oxide) glycol, poly(tetramethylene oxide) glycol (PO4G), etc. In the examples, the soft segments are based on PO4G and tetrahydrofuran/3-methyl tetrahydrofuran.
JP 2000-256919 discloses a thermo-adhesive polyester conjugate fiber containing a polyether ester-type block copolymer having a hard segment consisting of a polytrimethylene terephthalate polyester and a soft segment component consisting of a poly(alkylene oxide) glycol having an average molecular weight of 400-5,000. Poly(1,2-propylene oxide) glycol, poly(ethylene oxide) glycol, and poly(tetramethylene oxide) glycol are among the disclosed soft segments, and the later is preferred. The conjugate fiber also contains a polytrimethylene terephthalate polyester section.
All of the aforementioned documents are incorporated herein by reference.
TPEs based on those exemplified in the prior art are primarily based on PO4G, copolymers of tetrahydrofuran and 3-alkyltetrahydrofuran, PEG, PPG and copolymers of these. While a range of polyether ester TPEs can be produced based on these polyethers, there remains the need for an overall improvement in physical properties, including tensile strength, elongation, and stretch-recovery properties, including tensile set and recovery power. The present invention provides distinct advantages toward achieving an overall improved balance of these properties. Particularly unexpected are a large increase in recovery power and a large decrease in stress decay.
The invention is directed to a polyether ester elastomer comprising about 90-about 60 weight % polytrimethylene ether ester soft segment and about 10-about 40 weight % trimethylene ester hard segment. They preferably contain at least about 70 weight %, more preferably at least about 74 weight %, polytrimethylene ether ester soft segment, and preferably contain up to about 85, more preferably up to about 82 weight %, polytrimethylene ether ester soft segment. They preferably contain at least about 15 weight %, more preferably at least about 18 weight %, and preferably contain up to about 30 weight %, more preferably up to about 26 weight %, trimethylene ester hard segment.
The mole ratio of hard segment to soft segment is preferably at least about 2.0, more preferably at least about 2.5, and is preferably up to about 4.5, more preferably up to about 4.0.
The polyether ester preferably has an inherent viscosity of at least about 1.4 dl/g, more preferably at least about 1.6 dl/g, and preferably up to about 2.4 dl/g, more preferably up to about 1.9 dl/g.
The polyether ester is preferably prepared by providing and reacting (a) polytrimethylene ether glycol, (b) 1,3-propanediol and (c) dicarboxylic acid, ester, acid chloride or acid anhydride.
In a preferred embodiment, at least 40 weight % of the polymeric ether glycol used to form the polytrimethylene ether ester soft segment is the polytrimethylene ether glycol, and up to 60 weight % of the polymeric ether glycol used to form the polytrimethylene ether ester soft segment is polymeric ether glycol preferably selected from the group consisting of polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, and copolymers of tetrahydrofuran and 3-alkyl tetrahydrofuran, and mixtures thereof.
In a preferred embodiment, at least 85 weight % of the polymeric ether glycol used to form the polytrimethylene ether ester soft segment is the polytrimethylene ether glycol.
Preferably, the polytrimethylene ether glycol has number average molecular weight of at least about 1,000, more preferably at least about 1,500. Preferably, the polytrimethylene ether glycol has number average molecular weight of less than about 5,000, more preferably up to about 3,500.
In a preferred embodiment, at least 75 mole % of the diol used to form the trimethylene ester hard segment is 1,3-propanediol and up to 25 mole % of the diol are diol other than 1,3-propanediol preferably with 2-15 carbon atoms, more preferably selected from ethylene, isobutylene, butylene, pentamethylene, 2,2-dimethyltrimethylene, 2-methyltrimethylene, hexamethylene and decamethylene glycols, dihydroxy cyclohexane, cyclohexane dimethanol, hydroquinone bis(2-hydroxyethyl) ether, and mixtures thereof.
Preferred diol other than 1,3-propanediol contain 2-8 carbon atoms. Most preferred are ethylene glycol and 1,4-butanediol, and mixtures thereof.
In a preferred embodiment, at least 85 mole % of the diol used to form the trimethylene ester hard segment is 1,3-propanediol.
Preferably, the dicarboxylic acid, ester, acid chloride or acid anhydride is an aromatic dicarboxylic acid or ester, more preferably selected from the group consisting of dimethyl terephthalate, bibenzoate, isophthlate, phthalate and naphthalate; terephthalic, bibenzoic, isophthalic, phthalic and naphthalic acid; and mixtures thereof. More preferred are the aromatic diesters.
In a preferred embodiment, at least 50 mole % (more preferably at least 70 mole % and even more preferably at least 85 mole %) of the dicarboxylic acid, ester, acid chloride or acid anhydride is selected from the group consisting of terephthalic acid and dimethyl terephthalate.
In another preferred embodiment, the dicarboxylic acid, ester, acid chloride or acid anhydride are selected from the group consisting of terephthalic acid and dimethyl terephthalate.
In another embodiment, the invention is directed to the polyether ester being prepared by providing and reacting polytrimethylene ether glycol and polytetramethylene ester.
In one embodiment, the invention is directed to a polyether ester comprising a soft segment represented by the structure: 
and a hard segment represented by the structure: 
where x is about 17 to about 86 and R and Rxe2x80x2, which may be the same or different, are divalent radicals remaining after removal of carboxyl functionalities from a dicarboxylic acid equivalent.
The invention is also directed to fibers prepared from the polyether ester.
Preferred fibers include monocomponent filament, staple fiber, multicomponent fiber such as bicomponent fiber (containing the polyether ester as at least one component). The fibers are used to prepare woven, knit and nonwoven fabric.
The invention is further directed to the processes of preparing the polyether ester, fibers and fabrics.
The polyether esters of this invention can be used to prepare melt spinnable thermoplastic elastomers having excellent strength and stretch-recovery properties, not heretofore achieved.
The invention is directed to a polyether ester elastomer comprising about 90-about 60 weight % polytrimethylene ether ester soft segment and about 10-about 40 weight % trimethylene ester hard segment. They preferably contain at least about 70 weight %, more preferably at least about 74 weight %, polytrimethylene ether ester soft segment, and preferably contain up to about 85, more preferably up to about 82 weight %, polytrimethylene ether ester soft segment. They preferably contain at least about 15, more preferably at least about 18 weight %, and preferably contain up to about 30 weight %, more preferably up to about 26 weight %, trimethylene ester hard segment.
The polyether ester preferably has an inherent viscosity of at least about 1.4 dl/g, more preferably at least about 1.6 dl/g, and preferably up to about 2.4 dl/g, more preferably up to about 1.9 dl/g.
Herein, xe2x80x9cpolytrimethylene ether ester soft segmentxe2x80x9d and xe2x80x9csoft segmentxe2x80x9d are used to refer to the reaction product of polymeric ether glycol and dicarboxylic acid equivalent which forms an ester connection, wherein at least 40 weight % of the polymeric ether glycol used to form the soft segment is polytrimethylene ether glycol (PO3G). Preferably at least 45 weight %, more preferably at least 50 weight %, even more preferably at least 85 weight %, and most preferably about 95-100 weight %, of the polymeric ether glycol used to form the soft segment is PO3G.
When referring to the polytrimethylene ether glycol, dicarboxylic acid equivalent, etc., it should be understood that reference is to one or more of these items. Thus, for instance, when referring to at least 40 weight % of the polymeric ether glycol used to form the soft segment being polytrimethylene ether glycol, it should be understood that one or more polytrimethylene ether glycol can be used.
When PO3G is used to form the soft segment, it can be represented as comprising units represented by the following structure: 
wherein R represents a divalent radical remaining after removal of carboxyl functionalities from a dicarboxylic acid equivalent.
A wide range of molecular weights of the PO3G can be used. Preferably the PO3G has a number average molecular weight (Mn) of at least about 1,000, more preferably at least about 1,500, and most preferably at least about 2,000. The Mn is preferably less than about 5000, more preferably less than about 4,000, and most preferably less than about 3,500. Therefore, x in the above formula is at least about 17, more preferably at least about 25 and most preferably at least about 34, and is less than about 86, more preferably less than about 67 and most preferably less than about 60. PO3G""s useful for this invention are described in U.S. patent application Ser. Nos. 09/738,688 and 09/738,689, both filed Dec. 15, 2000 (now U.S Patent Application Publication Nos. 2002/0007043 A1 and 2002/0010374 A1), and their PCT counterparts WO 01/44348 and 01/44150, all of which are incorporated herein by reference.
PO3G can be prepared by any process known in the art. For example, PO3G can be prepared by dehydration of 1,3-propanediol or by ring opening polymerization of oxetane. The process is irrelevant so long as the polyether glycol meets the specifications for the final polymer product. Methods for making PO3G are described in U.S. patent application Ser. Nos. 09/738,688 and 09/738,689, both filed Dec. 15, 2000 (now U.S. Patent Application Publication Nos. 2002/0007043 A1 and 2002/0010374 A1), and their PCT counterparts WO 01/44348 and 01/44150, all of which are incorporated herein by reference.
Up to 60 weight % of the soft segment may comprise polymeric ether glycol other than PO3G. Preferred are those selected from the group consisting of polyethylene ether glycol (PEG), polypropylene ether glycol (PPG), polytetramethylene ether glycol (PO4G), polyhexamethylene ether glycol, and copolymers of tetrahydrofuran and 3-alkyl tetrahydrofuran (THF/3MeTHF). The other polymeric ether glycols preferably have a number average molecular weight of at least about 1,000, more preferably at least about 1,500, and preferably up to about 5,000, more preferably up to about 3,500. An especially important copolymer is the copolymer of tetrahydrofuran and 3-methyl tetrahydrofuran (THF/3MeTHF). Preferably up to 55 weight %, more preferably up to 50 weight %, and most preferably up to 15 weight %, of the polyethylene ether glycol used to form the soft segment is PO3G.
By xe2x80x9ctrimethylene ester hard segmentxe2x80x9d and xe2x80x9chard segmentxe2x80x9d reference is to the reaction product of diol(s) and dicarboxylic acid equivalent which forms an ester connection, wherein greater than 50 mole %, more preferably at least 75 mole %, even more preferably at least 85 mole % and most preferably 95-100 mole %, of the diol used to form the hard segment is 1,3-propanediol.
When 1,3-propanediol is used to form the hard segment, the hard segment can be represented as comprising units having the following structure: 
Rxe2x80x2 represents a divalent radical remaining after removal of carboxyl functionalities from a dicarboxylic acid equivalent. In most cases, the dicarboxylic acid equivalents used to prepare the soft segment and the hard segment of the polyether ester of this invention will be the same.
The hard segment can also be prepared with less than 50 mole % (preferably up to 25 mole %, more preferably up to 15 mole %), of diols other than butylene diol. They preferably have a molecular weight lower than 400 g/mol. The other diols are preferably aliphatic diols and can be acyclic or cyclic. Preferred are diols with 2-15 carbon atoms such as ethylene, isobutylene, butylene, pentamethylene, 2,2-dimethyltrimethylene, 2-methyltrimethylene, hexamethylene and decamethylene glycols, dihydroxy cyclohexane, cyclohexane dimethanol, hydroquinone bis(2-hydroxyethyl) ether. Especially preferred are aliphatic diols containing 2-8 carbon atoms. Most preferred are diols selected from the group consisting of ethylene glycol and 1,4-butanediol. Two or more other diols can be used.
By xe2x80x9cdicarboxylic acid equivalentxe2x80x9d is meant dicarboxylic acids and their equivalents from the standpoint of making the compounds of this invention, as well as mixtures thereof. The equivalents are compounds which perform substantially like dicarboxylic acids in reaction with glycols and diols.
The dicarboxylic acid equivalents can be aromatic, aliphatic or cycloaliphatic. In this regard, xe2x80x9caromatic dicarboxylic acid equivalentsxe2x80x9d are dicarboxylic acid equivalents in which each carboxyl group is attached to a carbon atom in a benzene ring system such as those mentioned below. xe2x80x9cAliphatic dicarboxylic acid equivalentsxe2x80x9d are dicarboxylic acid equivalents in which each carboxyl group is attached to a fully saturated carbon atom or to a carbon atom which is part of an olefinic double bond. If the carbon atom is in a ring, the equivalent is xe2x80x9ccycloaliphatic.xe2x80x9d
The dicarboxylic acid equivalent can contain any substituent groups or combinations thereof, so long as the substituent groups do not interfere with the polymerization reaction or adversely affect the properties of the polyether ester product. Dicarboxylic acid equivalents include dicarboxylic acids, diesters of dicarboxylic acids, and diester-forming derivatives such as acid halides (e.g., acid chlorides) and anhydrides.
Especially preferred are the dicarboxylic acid equivalents selected from the group consisting of dicarboxylic acids and diesters of dicarboxylic acids. More preferred are dimethyl esters of dicarboxylic acids.
Preferred are the aromatic dicarboxylic acids or diesters by themselves, or with small amounts of aliphatic or cycloaliphatic dicarboxylic acids or diesters. Most preferred are the dimethyl esters of aromatic dicarboxylic acids.
Representative aromatic dicarboxylic acids useful in the present invention include terephthalic acid, isophthalic acid, bibenzoic acid, naphthalic acid, substituted dicarboxylic compounds with benzene nuclei such as bis(p-carboxyphenyl)methane, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, 4,4xe2x80x2-sulfonyl dibenzoic acid, etc., and C1-C10 alkyl and other ring substitution derivatives such as halo, alkoxy or aryl derivatives. Hydroxy acids such as p-(hydroxyethoxy)benzoic acid can also be used providing an aromatic dicarboxylic acid is also present. Representative aliphatic and cycloaliphatic dicarboxylic acids useful in this invention are sebacic acid, 1,3- or 1,4-cyclohexane dicarboxylic acid, adipic acid, dodecanedioic acid, glutaric acid, succinic acid, oxalic acid, azelaic acid, diethylmalonic acid, fumaric acid, citraconic acid, allylmalonate acid, 4-cyclohexene-1,2-dicarboxylate acid, pimelic acid, suberic acid, 2,5-diethyladipic acid, 2-ethylsuberic acid, 2,2,3,3-tetramethyl succinic acid, cyclopentanenedicarboxylic acid, decahydro-1,5- (or 2,6-)naphthalene dicarboxylic acid, 4,4xe2x80x2-bicyclohexyl dicarboxylic acid, 4,4xe2x80x2methylenebis(cyclohexylcarboxylic acid), 3,4-furan dicarboxylate, and 1,1-cyclobutane dicarboxylate. The dicarboxylic acid equivalents in the form of diesters, acid halides and anhydrides of the aforementioned aliphatic dicarboxylic acids are also useful to provide the polyether ester of the present invention. Representative aromatic diesters include dimethyl terephthalate, bibenzoate, isophthlate, phthalate and naphthalate.
Of the above, preferred are terephthalic, bibenzoic, isophthalic and naphthalic acid; dimethyl terephthalate, bibenzoate, isophthlate, naphthalate and phthalate; and mixtures thereof. Particularly preferred dicarboxylic acid equivalents are the equivalents of phenylene dicarboxylic acids especially those selected from the group consisting of terephthalic and isophthalic acid and their diesters, especially the dimethyl esters, dimethyl terephthalate and dimethyl isophthalate. In addition, two or more dicarboxylic acids equivalents can be used. For instance, terephthalic acid or dimethyl terephthalate can be used with small amounts of the other dicarboxylic acid equivalents. In one example, a mixture of diesters of terephthalic acid and isophthalic acid was used.
In a preferred embodiment, at least 50 mole % (more preferably at least 70 mole %, even more preferably at least 85 mole % and most preferably about 95-100 mole %) of the dicarboxylic acid, ester, acid chloride or acid anhydride is selected from the group consisting of terephthalic acid and dimethyl terephthalate.
The polyether ester is preferably prepared by providing and reacting (a) polytrimethylene ether glycol, (b) 1,3-propanediol and (c) dicarboxylic acid, ester, acid chloride or acid anhydride. The other glycols, diols, etc., as described above are can also be provided and reacted.
The polyether ester of this invention is conveniently made starting with a conventional ester exchange reaction, esterification or transesterification depending on the starting dicarboxylic acid equivalent. For example, dimethyl terephthalate is heated with polytrimethylene ether glycol and an excess of 1,3-propanediol in the presence of a catalyst at 150-250xc2x0 C., while distilling off the methanol formed by the ester exchange. This reaction is typically performed at a pressure of about 1 atmosphere. The reaction product is a mixture of the ester exchange reaction products of the dimethyl terephthalate and the polytrimethylene ether glycol and 1,3-propanediol, primarily bis(hydroxybutyl) terephthalate with varying amounts of (hydroxy-polytrimethylene ether) terephthalates with a small amount of the corresponding oligomers. This mixture then undergoes polymerization or polycondensation to a copolymer of an elastomeric polyether ester with a polytrimethylene ether glycol soft segment and a trimethylene terephthalate hard segment (condensation product of 1,3-propanediol and dimethyl terephthalate). The polymerization (polycondensation) involves additional ester exchange and distillation to remove the diol to increase molecular weight. The polycondensation is typically performed under vacuum. Pressure is typically in the range of 0.01 to 18 mm Hg (1.3 to 2400 Pa), preferably in the range of 0.05 to 4 mm Hg (6.7 to 553 Pa) and most preferably 0.05 to 2 mm Hg. The polycondensation is typically run at a temperature in the range of about 220xc2x0 C. to 260xc2x0 C.
The ester exchange and polymerization steps may involve alternative processes than those described above. For example, polytrimethylene ether glycol can be reacted with polytrimethylene ester (e.g., polytrimethylene terephthalate) in the presence of catalyst (such as those described for the ester exchange, preferably the titanium catalysts such as tetrabutyl titanate) until randomization occurs. Both processes result in block copolymers.
To avoid excessive residence time at high temperatures and possible accompanying thermal degradation, a catalyst can be employed in the ester exchange. Catalysts useful in the ester exchange process include organic and inorganic compounds of titanium, lanthanum, tin, antimony, zirconium, and zinc. Titanium catalysts, such as tetraisopropyl titanate and tetrabutyl titanate, are preferred and are added in an amount of at least about 25 ppm (preferably at least about 50 ppm and more preferably at least about 70 ppm) and up to about 1,000 ppm (preferably up to about 700 ppm and more preferably up to about 400 ppm) titanium by weight, based on the weight of the finished polymer. Tetraisopropyl titanate and tetrabutyl titanate are also effective as polycondensation catalysts. Additional catalyst may be added after ester exchange or direct esterification reaction and prior to polymerization. Preferably the catalyst is tetrabutyl titanate (TBT).
Ester exchange polymerizations are generally conducted in the melt without added solvent, but inert solvents can be added to facilitate removal of volatile components, such as water and diols at low temperatures. This technique is useful during reaction of the polytrimethylene ether glycol or the diol with the dicarboxylic acid equivalent, especially when it involves direct esterification, i. e., the dicarboxylic acid equivalent is a diacid. Other special polymerization techniques can be useful for preparation of specific polymers. Polymerization (polycondensation) can also be accomplished in the solid phase by heating divided solid product from the reaction of polytrimethylene ether glycol, a dicarboxylic acid equivalent, and 1,3-propanediol in a vacuum or in a stream of inert gas to remove liberated diol. This type of polycondensation is referred to herein as xe2x80x9csolid phase polymerizationxe2x80x9d (or abbreviated xe2x80x9cSPPxe2x80x9d).
Batch or continuous methods can be used for the processes described above or for any stage of polyether ester preparation. Continuous polymerization, by ester exchange, is preferred.
In preparing the polyether ester elastomers of this invention, it is sometimes desirable to incorporate known branching agents to increase melt strength. In such instances, a branching agent is typically used in a concentration of 0.00015 to 0.005 equivalents per 100 grams of polymer. The branching agent can be a polyol having 3-6 hydroxyl groups, a polycarboxylic acid having 3 or 4 carboxyl groups, or a hydroxy acid having a total of 3-6 hydroxyl and carboxyl groups. Representative polyol branching agents include glycerol, sorbitol, pentaerytritol, 1,1,4,4-tetrakis(hydroxymethyl)cyclohexane, trimethylol propane, and 1,2,6-hexane triol. Suitable polycarboxylic acid branching agents include hemimellitic, trimellitic, trimesic pyromellitic, 1,1,2,2-ethanetetracarboxylic, 1,1,2-ethanetricarboxylic, 1,3,5-pentanetricarboxylic, 1,2,3,4-cyclopentanetetracarboxylic and like acids. Although the acids can be used as is, it is preferred to use them in the form of their lower alkyl esters.
Properties of the polyether ester will be influenced by varying the composition (dicarboxylic acid equivalent, 1,3-propanediol, polytrimethylene ether glycol, other diol, other glycol, etc.), the weight percent of hard segment, and the mole ratio of hard segment to soft segment.
The preferred mole ratio of hard segment repeat units per soft segment (HS/SS) will depend on the composition of the hard segment repeat units, the weight percent hard segment, and the molecular weight of the polyether glycol. The mole ratio of hard segment to soft segment is preferably at least about 2.0, more preferably at least about 2.5, and is preferably up to about 4.5, more preferably up to about 4.0. When the ratio is below the minimum value of the range, the polymer may possess an undesirably low tenacity and low melting temperature. At ratios higher than 5, difficulties may be encountered in melt processing the polymer. The best balance of processability and properties are obtained with copolymers having a mole ratio of hard segment to soft segment of 2.5-4.0.
The polyether esters of this invention are useful in making fibers, films and other shaped articles.
The fibers include monocomponent and multicomponent fiber such as bicomponent fiber (containing the polyether ester as at least one component), and can be continuous filaments or staple fiber. The fibers are used to prepare woven, knit and nonwoven fabric. The nonwoven fabrics can be prepared using conventional techniques such as use for meltblown, spunbonded and card and bond fabrics, including heat bonding (hot air and point bonding), air entanglement, etc.
The fibers are preferably at least about 10 denier (11 dtex), and preferably are up to about 2,000 denier (2,200 dtex), more preferably up to about 1,200 denier (1,320 dtex), and most preferably up to about 120 denier (132 dtex).
Spinning speeds can be at least about 200 meters/minute (m/min), more preferably at least about 400 m/min, and ever more preferably at least about 500 m/min, and can be up to about 1,200 m/min or higher.
The fibers can be drawn from about 1.5xc3x97 to about 6xc3x97, preferably at least about 1.5 xc3x97 and preferably up to about 4xc3x97. Single step draw is the preferred drawing technique. In most cases it is preferred not to draw the fibers.
The fibers can be heat set, and preferably the temperature is at least about 140xc2x0 C. and preferably up to about 160xc2x0 C.
Finishes can be applied for spinning or subsequent processing, and include silicon oil, mineral oil, and other spin finishes used for polyesters and polyether ester elastomers, etc.
The fibers are stretchy, have good chlorine resistance, can be dyed under normal polyester dyeing conditions, and have excellent physical properties, including superior strength and stretch recovery properties, particularly improved unload power and stress decay.
Conventional additives can be incorporated into the polyether ester or fiber by known techniques. The additives include delusterants (e.g., TiO2, zinc sulfide or zinc oxide), colorants (e.g., dyes), stabilizers (e.g., antioxidants, ultraviolet light stabilizers, heat stabilizers, etc.), fillers, flame retardants, pigments, antimicrobial agents, antistatic agents, optical brightners, extenders, processing aids, viscosity boosters, and other functional additives.